The use of thermal energy to destroy bodily tissue can be applied to a variety of therapeutic procedures, including the destruction of tumors. Thermal energy can be imparted to the tissue using various forms of energy, such as radio frequency electrical energy, microwave or light wave electromagnetic energy, or ultrasonic vibrational energy. Radio frequency (RF) ablation, for example, can be effected by placing one or more electrodes against or into tissue to be treated and passing high frequency electrical current into the tissue. The current can flow between closely spaced emitting electrodes or between an emitting electrode and a larger, common electrode located remotely from the tissue to be heated.
One disadvantage with these techniques is that maximum heating often occurs at or near the interface between the therapeutic tool and the tissue. In RF ablation, for example, maximum heating can occur in the tissue immediately adjacent to the emitting electrode. This can reduce the conductivity of the tissue, and in some cases, can cause water within the tissue to boil and become water vapor. As this process continues, the impedance of the tissue can increase and prevent current from entering into the surrounding tissue. Thus, conventional RF instruments are limited in the volume of tissue that can be treated.
Fluid enhanced ablation therapy, such as the SERF™ ablation technique (Saline Enhanced Radio Frequency™ ablation), can treat a greater volume of tissue than conventional RF ablation. The SERF ablation technique is described in U.S. Pat. No. 6,328,735, which is hereby incorporated by reference in its entirety. Using the SERF ablation technique, saline is passed through a needle and heated, and the heated fluid is delivered to the tissue immediately surrounding the needle. The saline helps distribute the heat developed adjacent to the needle and thereby allows a greater volume of tissue to be treated with a therapeutic dose of ablative energy. The therapy is usually completed once a target volume of tissue reaches a desired therapeutic temperature, or otherwise receives a therapeutic dose of energy.
Fluid enhanced ablation therapy can be administered to a patient in a variety of manners. For example, an RF electrode can be introduced into a patient's body percutaneously using a needle during a laparoscopic or other minimally invasive surgical procedure. In such a procedure, a surgeon, doctor, interventional radiologist, or other medical professional administering the therapy must utilize a medical imaging apparatus to guide the positioning of the RF electrode at a desired location. Such an imaging apparatus can also be utilized to monitor the effectiveness of the therapy as the procedure progresses.
Many medical imaging apparatuses, however, require a patient to be placed in a space-constrained volume within the apparatus in order to be effectively imaged. X-ray Computed Tomography (CT) scanners and Magnetic Resonance Imaging (MRI) scanners, for example, often require a patient to be moved through a small cylindrical opening in the device. Moving a patient through these devices while long needles and extended manipulating handles are protruding from their body can be difficult or impossible. Professionals administering the therapy can be forced to remove the devices from the patient and subsequently reintroduce them several times in order to successfully image and treat the targeted area of the patient's body.
Accordingly, there is a need for improved low profile fluid enhanced ablation therapy devices and methods that can be utilized by medical professionals in space-constrained environments, such as within medical imaging apparatuses.